Method of regulating pressure with an intraocular implant

ABSTRACT

An ophthalmic implant for treatment of glaucoma, a delivery device for implanting such an implant, and a method of implanting such an implant. The implant includes a tube having an inlet end, an outlet end, and a tube passage therebetween, and a disk connected to the tube at the outlet end of the tube. The tube passage has a cross-sectional area sufficiently small to inhibit the flow of aqueous humor through the tube passage. The implant provides a bleb of aqueous humor under the conjunctiva so that the bleb and the elasticity of the conjunctiva assist in regulating the flow of aqueous humor through the tube as a function of the IOP. The tube at its inlet end has a beveled surface facing away from the iris and one or more circumferential holes. One or more retention projections are provided for anchoring and may be extended outwardly when the implant is implanted in the eyeball. The disk has an outer rim and one or more inner uprights. The implant is implanted by use of a delivery device comprising a handle and a rodlike instrument, with a tip for insertion into the tube passage of the implant and a retention mechanism for retaining the implant. During implantation, the implant is inserted through a slit in a portion of the conjunctiva which normally lies at a distance away from the intended implantation site.

This application is a continuation of prior application Ser. No.08/891,765, filed Jul. 14, 1997, now U.S. Pat. No. 5,968,058, which is acontinuation of application Ser. No. 08/711,377, filed Sep. 5, 1996, nowU.S. Pat. No. 5,702,414, which is a division of application Ser. No.08/623,238, filed Mar. 27, 1996, now U.S. Pat. No. 5,868,697.

FIELD OF THE INVENTION

The invention relates generally to ophthalmic implants for treatment ofglaucoma, delivery devices for implanting such implants, and to methodsof implanting such implants.

BACKGROUND OF THE INVENTION

Glaucoma is an eye condition characterized by an increase in theintraocular pressure (IOP) of the eye to an abnormal level. A normal eyemaintains a proper IOP by the circulation within the eye of aqueoushumor aqueous humor is secreted from the ciliary body, passes throughthe pupil into the anterior chamber of the eyeball, and is filtered outof the eyeball via the trabeculum and the Canal of Schlemm. Withglaucoma, the aqueous humor excretory pathway is blocked, the aqueoushumor cannot pass out of the eyeball at an adequate rate, the IOP rises,the eyeball becomes harder, and the optic nerve atrophies by thepressure applied on its fibers leaving the retina. A characteristicoptic neuropathy develops, resulting in progressive death of theganglion cells in the retina, restriction of the visual field, andeventual blindness. Advanced stages of the disease are characterizedalso by significant pain.

Glaucoma treatment, if initiated early in the course of the disease, canprevent further deterioration and preserve most of the ocular functions.The goal of glaucoma treatment is to reduce the IOP to a level which isconsidered safe for a particular eye, but which is not so low as tocause ocular malfunction or retinal complications.

One type of glaucoma treatment is filtration surgery, which provides analternate route for aqueous humor to exit the anterior chamber of theeyeball and enter the sub-conjunctival space, thereby lowering the IOP.In full thickness operations a fistula is created through the limbalsclera, connecting diregtly the anterior chamber of the eyeball and thesub-conjunctival space. Full thickness operations provide long-lastingcontrol of IOP; however, excessive loss of aqueous humor from theeyeball during the early postoperative period frequently leads tohypotony.

In guarded filtration surgery (trabeculectomy), a fistula createdthrough the limbal sclera is protected by an overlying partial thicknesssutured scleral flap. The scleral flap provides additional resistance toexcessive loss of aqueous humor from the eyeball, thereby reducing therisk of early postoperative hypotony. However, trabeculectomy may resultin higher eventual IOP and increased risk of late failure of filtration,compared with full thickness operations.

In accordance with one recently introduced procedure, a full thicknessfiltering fistula may be created by a holmium laser probe, with minimalsurgically induced trauma. After retrobulbar anesthesia, a conjunctivalincision (approximately 1 mm) is made about 12-15 mm posterior to theintended sclerostomy site, and a laser probe is advanced through thesub-conjunctival space to the limbus. Then, multiple laser pulses areapplied until a full thickness fistula is created. This technique hassometimes resulted in early hypotony on account of a difficulty incontrolling the sclerostomy size. In addition, early and late irisprolapse into the sclerostomy has resulted in abrupt closure of thefistula and eventual surgical failure. Further, despite its relativesimplicity, the technique still necessitates the use of retrobulbaranesthesia to avoid pain caused by the laser applications. The injectionof anesthetic material close to the already damaged optic nerve maysometimes lead to further visual damage. A further disadvantage of thisprocedure, as well as other types of glaucoma filtration surgery, is thepropensity of the fistula to be sealed by scarring.

Various attempts have been made to overcome the problems of filtrationsurgery, for example, by using ophthalmic implant devices. Typicalophthalmic implants utilize drainage tubes so as to maintain theintegrity of the openings formed in the eyeball for the relief of theIOP.

Typical ophthalmic implants suffer from several disadvantages. Forexample, the implants typically utilize a valve mechanism for regulatingthe flow of aqueous humor from the eyeball; defects in and/or failure ofsuch valve mechanisms could lead to excessive loss of aqueous humor fromthe eyeball and possible hypotony. The implants also tend to clog overtime, either from the inside by tissue, such as the iris, being suckedinto the inlet, or from the outside by the proliferation of cells, forexample by scarring. Additionally, the typical implant insertionoperation is complicated, costly and takes a long time.

U.S. Pat. No. 3,788,327 to Donowitz et al. shows a prior art implantutilizing a valve mechanism for regulating the flow of aqueous humorfrom the eyeball. As stated above, defects in and/or failure of such avalve mechanism could lead to excessive loss of aqueous humor from theeyeball and possible hypotony. Additionally, both the inlet opening andthe outlet opening in the implant shown in U.S. Pat. No. 3,788,327 maybe susceptible to clogging—the inlet opening by the iris and the outletopening by scarring. Finally, implantation of an implant according toU.S. Pat. No. 3,788,327 may involve the separate steps of firstproviding a tract for receiving the implant and/or suturing the implantonce it is in place, which add time and possible complications to theoperation.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved ophthalmicimplant which may be implanted into the eyeball for the treatment ofglaucoma, a delivery device for implanting such an implant, and animproved method of implanting such an implant into the eyeball.

In one embodiment of an improved implant in accordance with theinvention, an intraocular implant is provided to be implanted in theeyeball. The implant includes a tube having an inlet end, an outlet end,and a tube passage therebetween for permitting aqueous humor to flow outof the eyeball, and a disk connected to the tube at the outlet end ofthe tube. The tube passage may have a cross-sectional area sufficientlysmall to inhibit the flow of aqueous humor through the tube passage. Thecross-sectional area may be sufficiently small to prevent flow when theIOP is below a threshold amount.

The disk, which is designed to be located underneath the conjunctiva,may have an outer rim for forming a reservoir having an enlargedcross-sectional area relative to the cross-sectional area of the tubepassage. When aqueous humor flows through the tube passage, a bleb ofaqueous humor forms under the conjunctiva so that the bleb and theelasticity of the conjunctiva assist in regulating the flow of aqueoushumor through the tube as a function of the IOP.

To prevent clogging of the implant, the tube at its inlet end may beprovided with a beveled surface which faces away from the iris when theimplant is inserted. Additionally, one or more circumferential holes maybe provided along the tube for allowing aqueous humor to flow into thetube passage even if the axial inlet opening is blocked.

To prevent clogging at the outlet end, the disk may have an outer rim asdescribed above which raises the conjunctiva away from the axial outletof the tube passage to allow outflow. One or more inner uprights (whichmay be in the form of an inner rim) may also be provided on the disk forthis purpose. Clogging is further avoided by implanting the implantunder the conjunctiva at a distance away from an insertion slit in theconjunctiva, such that healing of the slit does not cause scar tissue toform in the area of the axial outlet opening of the implant.

Implantation may be facilitated by further features of the implant. Forexample, the implant may have one or more retention projections (forexample, in the form of a spur, flange, or plate). The retentionprojection may be rigid, or it may be made of an elastic material suchthat it is able to be flexed inward against the tube during penetrationthrough the sclera. Alternatively, the retention projection may bedesigned to lie initially relatively flat against the tube for easierpenetration through the sclera and to prevent tearing of the sclera,with a mechanism for extending the retention projection outwardly whenthe implant is implanted in the eyeball. For example, the retentionprojection may be extended outwardly by a separate expansion tool or maybe constructed of a shape memory material, such as PMMA of nitinol, sothat it is extended outwardly when subjected to the heat of the eyeball.One or more retention projections according to the invention aresufficient to reliably anchor the implant in the eyeball without theneed for sutures, saving time and costs.

Implantation may also be facilitated by the provision of one or moremarkers on the implant visible through the cornea upon passing throughthe sclera. For example, a circumferential hole as described above mayserve as a marker; alternatively, the marker may be some other suitablevisible mechanism, such as a scratch or colored mark on the tube. Thevisibility of the marker lets the doctor know that the marker has passedthrough the sclera, indicating that the implant is in place.

Implantation of an implant may be performed by use of a delivery devicein accordance with the invention, comprising a handle and a rodlikeinstrument, for example a needle or probe, for carrying the implant forinsertion into the eyeball. The delivery device has a tip for insertioninto the tube passage of the implant and a suitable retention mechanismfor preventing the implant from moving up the delivery device duringimplantation. The retention mechanism may also be constructed to preventthe implant from rotating during implantation to insure properorientation of the implant in the eyeball. The delivery device mayadditionally have a suitable expansion tool for extending one or moreretention projections of the implant outwardly once the projection orprojections have penetrated through the sclera.

In one embodiment of an improved method of implanting an implantaccording to the invention, a small slit is cut in a portion of theconjunctiva which normally lies at a distance away from the intendedimplantation site. As the implant itself is very small, the slit alsomay be very small, for example about 2 mm in length or less. The smallsize of the slit as well as its positioning at a distance away from theimplantation site, for example about 10 mm, helps prevent contaminationof the sclerostomy site and reduces the risk of infection.

The implant is placed through the slit, directed to the implantationsite, and inserted into the sclera at the implantation site. The scleramay be pierced either by a needle-like tip of the tube of the implantformed by a beveled surface at the inlet end of the tube as describedabove or by the tip of a needle of the delivery device which carries theimplant. Thus, the implant may be inserted directly into the eyeballwithout the need for any separate piercing step, resulting in cost andtime savings.

An intraocular implant, delivery device, and method of implantationaccording to the invention provide the advantages of a full thicknessfistula, while avoiding the limitations of the standard trabeculectomy.An implant according to the invention may be very small and implantablewithout surgery. No surgery room or hospitalization is necessary,thereby reducing costs. Implantation is minimally invasive, simple andquick, requiring only local anesthesia. Retrobulbar anaesthesia is notnecessary, and thus iatrogenic damage to the optic nerve is avoided.There is no need to perform an iridectomy, and thus aqueous flow ismaintained, lens nourishment is unaffected, and the likelihood ofcataracts developing as a result of the procedure is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a first embodiment of anintraocular implant according to the invention, shown inserted in aneyeball;

FIG. 2 is an enlarged perspective view of the intraocular implant ofFIG. 1;

FIG. 3 is a view similar to FIG. 2, with part of the intraocular implantcut away to show a sectional view thereof;

FIG. 4 is an enlarged perspective view of a disk portion of theintraocular implant of FIG. 1;

FIGS. 5 through 7 illustrate the action of the conjunctiva duringoperation of the intraocular implant of FIG. 1, with FIG. 5 showing astage of the operation without a bleb formed, FIG. 6 showing formationof a bleb, and FIG. 7 showing further formation of the bleb;

FIGS. 8 through 10 illustrate a delivery device and insertion of theintraocular implant of FIG. 1 into an eyeball; with FIG. 8 showing thedelivery device and implant before insertion, FIG. 9 showing thedelivery device and implant being placed through a slit in theconjunctiva, and FIG. 10 showing the implant after insertion with thedelivery device withdrawn;

FIG. 11 is an enlarged perspective view of a second embodiment of anintraocular implant according to the invention, with part of theintraocular implant cut away to show a sectional view thereof;

FIG. 12 is a top view of the intraocular implant of FIG. 11, showing adisk portion of the implant;

FIG. 13 illustrates a delivery device and insertion of the intraocularimplant of FIG. 11 into an eyeball;

FIG. 14 is a schematic cross-sectional view of the intraocular implantof FIG. 11, shown inserted in an eyeball; and

FIGS. 15 and 16 illustrate a third embodiment of an intraocular implantaccording to the invention, with FIG. 15 showing the implant prior toattachment of a retention plate and FIG. 16 showing the implant afterattachment of the retention plate;

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an intraocular implant 30, constructed in accordancewith an embodiment of the invention, implanted in an eyeball 10. Theimplant 30 comprises a needle-like tube 32 and a disk 34. The plane ofthe disk 34 forms an angle with the tube 32 that corresponds to theangle between the surface of the sclera 12 and the axis of insertion ofthe implant 30. The implant 30 is inserted in the sclera 12 of theeyeball 10, in the limbal area 14 adjacent to the cornea 16, andprotrudes into the anterior chamber 20 adjacent the iris 22. The implant30 is inserted so that the disk 34 is placed on a surface of the sclera12 underneath the conjunctiva 18. The implant 30 may be placed above orbelow the Tenon's capsule (not shown). It will be appreciated by personsof ordinary skill in the art that the exact location for inserting theimplant is not restricted to that shown, and may be any other suitableposition, such as behind the iris 22.

FIG. 2 shows an enlarged perspective view of the implant 30 of FIG. 1,and FIG. 3 shows a similar view, with part of the implant 30 cut away.The tube 32, which may take the form of a modified standard retrobulbartip, has an inlet end 40, an outlet end 50, and a tube passage 38extending therebetween, with the tube passage 38 having an axial inlet41 and an axial outlet 51. The disk 34 is connected to the tube 32 atits outlet end 50. The entire implant is very small; for example thetube 32 may have a length of about 2 mm and a width of about 0.5 mm, andthe disk 34 may have a diameter of about 1 mm and a thickness of lessthan 0.1 mm.

The tube passage 38 has a cross-sectional area sufficiently small toinhibit the flow of aqueous humor through the tube passage when. In oneembodiment, for example, the cylindrical tube passage 38 has a diameterof 300 micrometers. By using a specified internal cross-sectional areafor the tube passage, excessive loss of aqueous humor from the eyeballis prevented.

When the IOP is above a threshold amount, for example about 5 mm Hg,aqueous humor drains from the anterior chamber 20 of the eyeball 10through the axial inlet 41 and one or more circumferential holes 42,through the tube passage 38, and into the space under the conjunctiva18. The circumferential holes 42 may take any suitable form; forexample, they may be in the form of circular openings whose combinedcross-sectional area is equal to the cross-sectional area of the tubepassage 38. The circumferential holes 42 prevent the tube passage 38from becoming clogged at its inlet end because, even if the iris 22obstructs the axial inlet 41, aqueous humor can still pass through thecircumferential holes 42. In the event the axial inlet 41 is obstructed,the circumferential holes 42 also serve to cause a back pressure in thetube passage 38 to unclog the axial inlet 41. The circumferential holes42 serve the additional purpose of insuring a proper insertion both ofthe implant 30, as the upper hole is visible during implantation afterpenetration through the sclera and thus can be used as a marker. Toserve this function, any other suitable marker (such as a scratch orcolored mark) may be used.

The inlet end 40 of the tube 32 has a needle-like tip formed by abeveled surface 36, angled sharply for easy insertion into the eyeball.The beveled surface 36 increases the area of the axial inlet 41 toenlarge the entrance to the tube passage 38. The beveled surface 36 isdesigned to Lace away from the iris 22 to reduce the possibility ofobstruction of the axial inlet 41. Because the disk 34 is designed torest against the sclera 14 and the beveled surface 36 is designed toface away from the iris 22, the beveled surface 36 lies in a plane whichis angled opposite to the plane in which the disk 34 lies.

The tube 32 may have one or more retention projections in the form ofone or more spurs 52 provided integrally with it for retaining theimplant 30 in the eyeball 10 after insertion. Alternatively, theretention spur 52 may be made as a separate part connected to the tube32 by, for example, welding or brazing. The retention spur 52 may berigid, or it may be flexible such that it bends toward the tube 32during penetration of the sclera and springs outward to its originalshape after passing through the sclera. Alternatively, the retentionspur 52 may be designed for plastic deformation by a separate expansiontool (for example, a balloon) once it is in the eyeball 10, or theretention spur 52 may be constructed of a shape memory material, such asPMMA of nitinol, such that the spur is flat against the tube when coolbut expands to its final shape when subjected to the heat of the eyeball10.

The disk 34, shown enlarged in FIG. 4, comprises a base 44, an outer rim46, and a plurality of inner uprights 48. The areas between the uprights48 constitute passageways 56 for transverse flow of aqueous humor. Thebase 44 and outer rim 46 define a reservoir 54 such that, in operation,the aqueous humor flows out of the axial outlet 51 of the tube passage38, between the uprights 48, and into the reservoir 54. The passageways56 may be considered as part of the reservoir 54. The enlargedcross-sectional area of the reservoir 54 as compared to thecross-sectional area of the tube passage 38 provides a larger area forabsorption of the aqueous humor by the conjunctiva 18 and also acts inconjunction with the elasticity of the conjunctiva 18 to assist inregulating the flow of aqueous humor through the implant 30 as afunction of the IOP.

FIGS. 5 through 7 illustrate the action of the conjunctiva 18 duringoperation of the implant 30, in which it can be seen that the aqueoushumor which flows out of the tube passage forms a “bleb” 24 below theconjunctiva 18. It will be appreciated by persons having ordinary skillin the art that a higher IOP results in a higher flow rate through theimplant 30, and a greater force of the aqueous humor on the conjunctiva18.

In addition to defining the reservoir 54, the outer rim 46 of the disk34 serves the additional purpose of raising the conjunctiva 18 away fromthe axial outlet 51 to prevent clogging of the tube passage 38. Theinner uprights 48 also serve this purpose.

The shape of the disk 34 may be, but is not limited to, an ellipse, andit will be appreciated by persons having ordinary skill in the art thatit may conform to any shape which allows the implant to fit under theconjunctiva 18 and which regulates the IOP. The size and/or shape of thedisk 34 and/or the angle between the disk 34 and the tube 32 can also bechanged in order to use different implants for different persons eyes.

FIGS. 8 through 10 illustrate a delivery device 60 and a method ofinserting the intraocular implant 30 into an eyeball. The implant 30 isfirst attached to the delivery device 60, having a handle 62 and asuitable rodlike instrument 64 such as a needle or probe. The rodlikeinstrument 64 has a tip 70 for penetrating a tube passage of the implant30 and a retention mechanism for preventing the implant from moving upthe delivery device during implantation, for example in the form of anabutment surface 68 having an angle generally corresponding to that ofthe disk 34. This configuration also prevents rotation of the implant 30on the delivery device 60, thereby insuring proper orientation of theimplant in the eyeball. The retention mechanism may also include one ormore projections for extending inside the outer rim and/or between theinner uprights on the disk 34. In an alternative embodiment, theretention mechanism may be the tip of the rodlike instrument,constructed to engage the inside of the tube passage of the implant witha friction fit, thereby preventing the implant from moving up thedelivery device during implantation.

A delivery device 60 in which the rodlike instrument is a needle 65 isillustrated in FIG. 9. In that illustrated embodiment, the deliverydevice 60 is similar to a standard medical syringe having a housing anda needle 65 with a bore 67. The front tip 69 of the needle 65 isconfigured as an abutment surface having an angle generallycorresponding to that of the disk 34. The bore 67 of the needle 65 has atip in the form of a plug 71 which is configured to have across-sectional shape corresponding to that of the tube passage 38. Theimplant 30 is placed over the plug 71, with the end of the plug 71projecting into the tube passage 38, and with the front tip 69 of theneedle 65 abutting against the disk 34. The plug 71 blocks the tubepassage 38 during implantation.

To insert the implant 30 into the eyeball 10, a small slit 26 is cut ina portion of the conjunctiva 18 which normally lies at a distance awayfrom a portion 28 of the conjunctiva 18 which normally covers theintended implantation site. A small slit distanced away from theimplantation site, for example a 1-2 mm slit about 5-15 mm away from theimplantation site, reduces the possibility of aqueous humor flowing outof the conjunctiva through the slit, reduces the possibility ofinfection, reduces the possibility of scarring over the axial outlet ofthe implant, and facilitates closing and healing.

The implant 30, by delivery device 60, is passed through the slit 26,under the conjunctiva 18, to the implantation site in the sclera 14.FIG. 9 shows the advancement of the implant only schematically; it willbe appreciated that in practice the implant is directed from the slit tothe implantation site generally along the surface of the sclera, suchthat the longitudinal axis of the implant is generally parallel to thesurface of the sclera. Upon reaching the implantation site, the implantis tilted for penetration into the sclera. The acute angle of theneedle-like tip formed by the beveled surface 36 of the implant 30ensures that the implant 30 enters the sclera 14 easily. The needle-liketip penetrates through the sclera 14 into the anterior chamber 20 of theeyeball 10, while the disk 34 is pushed up against the sclera 14.

When the implant 30 is in place, as shown in FIG. 10, the retention spur(or spurs) 52 anchors the implant 30 in the eyeball 10 and prevents theimplant 30 from sliding out as the delivery device 60 is withdrawn. Theretention spur 52 also prevents the implant 30 from slipping out once inplace.

It will be appreciated by persons having ordinary skill in the art thatthe insertion of the implant is not restricted to the method describedabove, and it may be inserted by any of several methods known in theart. The delivery device may comprise an ‘internal’ or ‘external’needle. A straight or twisted guide wire, known in the art, may also beused to guide the delivery device to its precise position. To easeinsertion, the delivery device may be vibrated, or a lubricant, such asmedical paste or gel, can be spread onto the delivery device.Additionally, after implantation of the implant a suitable fibrosisinhibiting compound (e.g. 5FU, mitomycin) may be applied to theimplantation site.

FIG. 11 shows an alternative embodiment of an intraocular implant 130constructed in accordance with the invention. The implant 130 comprisesa tube 132 attached to an elliptical disk 134. The tube 132 has an inletend 140, an outlet end 150, and a tube passage 138, with the tubepassage 138 having an axial inlet 141, an axial outlet 151, andcircumferential holes 142 to drain the aqueous humor from the anteriorchamber 20 of the eyeball 10 into the space under the conjunctiva 18.

The distal end 152 of the tube 132 has a partially conical shape. Aplurality of retention projections in the form of retention flanges 158are formed on the outer circumference of the tube 132, approximatelyparallel to the disk 134, to act as anchors to retain the implant 130 inthe eyeball.

As shown in the enlarged view in FIG. 12, the disk 134 comprises anelliptical base 144, an outer rim 146, and an inner upright curved toform an inner rim 148, defining therebetween a reservoir 154. Aplurality of “U”-shaped passageways 156 are formed in the inner rim 148for allowing acueous humor to flow from the axial outlet 151 into thereservoir 154. The outer rim 146 and the inner rim 148 prevent theconjunctiva 18 from clogging the axial outlet 151.

As shown in FIG. 12, the disk 134 is elliptical in shape. The longeraxis of the disk 134 is approximately twice the diameter of the tube132, and the disk 134 is eccentrically displaced relative to the tube132. The elliptical shape and placement of the disk 134 allows a wideanchoring area for the implant 130 and maximizes the outlet drainagearea on the longer axis of the ellipse. The shorter axis of the ellipseenables the implant 130 to fit within the narrow space under theconjunctiva 18.

FIG. 13 illustrates a delivery device 160 and a method of inserting theintraocular implant 130 into an eyeball. The implant 130 is slidablyfixed over a needle 164 of the delivery device 160, which, similar to astandard medical syringe, has needle 164 attached to a housing 162. Thetip 174 of needle 164, which passes through the implant 130, is acutelyangled so that the tip 174 is generally in line with the angle of thelower part of the implant 130.

A front surface of the delivery device 160 is formed as an abutmentsurface angled to match the angle of the disk 134 and further comprisesan indent 172 to hold the implant 130 in place during implantation. Theshape of the delivery device 160 and the angled surface of the disk 134prevent the implant 130 from rotating during implantation. The

The delivery device 160 shown in FIG. 13 is used in a manner similar tothat described above with reference to FIGS. 8 through 10. In thisembodiment, however, the acute angle of the needle tip 174 pierces thesclera. The angled inlet end of the implant device 130 follows theneedle tip 174 through the sclera 14, into the anterior chamber 20 ofthe eyeball. As shown in FIG. 14, the retention flanges 158 anchor theimplant 130 in position and prevent the implant 130 from sliding out asthe delivery device 160 is withdrawn. The anchorage of the retentionflanges 158 also prevents the implant 130 from slipping out once inplace.

FIGS. 15 and 16 illustrate a third embodiment of an intraocular implantaccording to the invention. This embodiment is similar to that shown inFIGS. 1 through 10, with the exception that a separately attachedretention projection in the form of a retention plate 252 is used foranchoring instead of the retention spur 52. The retention plate isinserted into a groove 253 in the tube of the implant 230 and may befastened by any suitable means, for example by welding in the case of animplant 230 constructed of stainless steel.

An intraccular implant constructed in accordance with the invention maybe manufactured entirely from or covered with any suitable material suchas stainless steel, silicon, gold, nitinol, Teflon, tantalum, PMMA, orany other suitable plastic or other material. The implant may also becoated with heparin or any other suitable biology active compound.

Manufacture of an intraocular implant in accordance with the inventionmay be carried out according to the following process. The tube may beformed from the tip of a standard stainless steel hypodermic needle.Using an EDM machine, small holes are drilled proximate the tip of theneedle to form the circumferential holes. At a distance from the tipcorresponding to the desired length of the tube, the needle is cut atthe appropriate angle to correspond to the desired angle of the disk.The side of the needle is then undercut to form a projection which canbe later bent outwardly to form the spur.

The disk may be chemically etched from a stainless steel sheet accordingto the following process. A pattern of the disk is drawn on a computeraided design (CAD) system and plotted on a transparent film using alaser plotter. Plottings are made of both the upper side and the lowerside of the disk. The plotting for the upper side, for example, includesthe outer rim and the inner uprights; the plotting for the lower side,for example, includes the base of the disk.

A layer of photoresist is adhered to both surfaces of the stainlesssteel sheet. The photoresist is then exposed to UV light through thefilm on which the plottings are made. The areas of the sheet which areblocked by the plottings are not exposed. The photoresist which has beenexposed to UV light is then chemically removed.

Using an etching chemical, the stainless steel sheet is then etched, sothat the chemical eats away the areas of the sheet from which thephotoresist has been removed. The etching is time-controlled such thatthe chemical takes away material only to a predetermined depth.

By use of a plotting for the upper side which includes the outer rim andthe uprights, the chemical on the upper surface of the sheet takes awaymaterial on the outside of the disk, in the reservoir including betweenthe uprights, and in the center of the disk which is to receive thetube. Because the etching is time-controlled, the chemical acting on thetop of the sheet takes away material only part way through the thicknessof the sheet. By use of a plotting for the lower side which includes thebase of the disk, the chemical on the lower surface of the sheet takesaway material on the outside of the disk and in the center of the diskwhich is to receive the tube. The chemical acting on the bottom of thesheet takes away material part way through the thickness of the sheet.Because of action from both the top and the bottom, the material on theoutside of the disk and in the center of the disk which is to receivethe tube is completely taken away by the etching process through theentire thickness of the sheet. A small projection may be left on theoutside of the disk during the etching process to prevent the disk frombeing dislodged from the sheet.

It will be appreciated by persons having ordinary skill in the art thatvariations on this manufacturing process and other manufacturingprocesses are possible. For example, an implant made of plastic may bemanufactured by a suitable molding operation.

As will also be appreciated by persons having ordinary skill in the art,the various embodiments of intraocular implants, delivery devices, andmethods for implantation described hereinabove are given by way ofexample only. Various changes, modifications and variations may beapplied to the described embodiments without departing from the scope ofthe invention, defined by the appended claims.

What is claimed is:
 1. A method of regulating an intraocular pressure ofan eyeball comprising the steps of: (i) providing an intraocular implantcomprising: (a) a tube for implanting into the eyeball, said tubecomprising an inlet end, an outlet end, and a tube passage extendingbetween the inlet end and the outlet end for permitting aqueous humor toflow out of the eyeball, and (b) a subconjunctival flange connected tothe tube at the outlet end of the tube for placing on a surface of thesclera under the conjunctiva; (ii) cutting a slit in a portion of theconjunctiva of the eyeball which normally lies at a distance away froman implantation site; (iii) placing the implant through the slit in theconjunctiva; (iv) directing the implant between the sclera and theconjunctiva to the implantation site; and (v) inserting the implantthrough the sclera at the implantation site, including implanting thetube into the sclera and placing the subconjunctival flange on a surfaceof the sclera under the conjunctiva.
 2. A method of regulating anintraocular pressure according to claim 1, wherein the subconjunctivalflange of the intraocular implant lies substantially in a plane formingan oblique angle with a longitudinal axis of the tube; wherein theintraocular implant further comprises at least one retention projectionextending outwardly from the tube for anchoring the intraocular implantin the eyeball; and wherein the intraocular implant has at least oneside opening which opens into the tube passage proximate the inlet endof the tube.
 3. A method of regulating an intraocular pressure accordingto claim 2 wherein the intraocular implant is made of a plasticmaterial.
 4. A method of regulating an intraocular pressure according toclaim 2 wherein the intraocular implant is made of silicone.
 5. A methodof regulating an intraocular pressure according to claim 2 wherein theintraocular implant is made by a molding operation.
 6. A method ofregulating an intraocular pressure according to claim 2 wherein theintraocular implant is made of metal.
 7. A method of regulating anintraocular pressure according to claim 2 wherein the at least oneretention projection and the tube are made from separate pieces that arejoined together.
 8. A method of regulating an intraocular pressureaccording to claim 7 wherein the separate pieces forming the at leastone retention projection and the tube are joined together by welding. 9.A method of regulating an intraocular pressure according to claim 2wherein the tube passage is cylindrical, and wherein a diameter of thetube passage is substantially smaller than a length of the tube passage.10. A method of regulating an intraocular pressure according to claim 9wherein the diameter of the tube passage is about 300 micrometers orless.
 11. A method of regulating an intraocular pressure according toclaim 1, wherein the subconjunctival flange of the intraocular implanthas an inner sclera-facing surface and an outer conjunctiva-facingsurface such that, upon implantation, the inner sclera-facing surfacefaces the sclera of the eyeball and the outer conjunctiva-facing surfacefaces the conjunctiva of the eyeball, wherein the subconjunctival flangelies substantially in a plane forming an oblique angle with alongitudinal axis of the tube; and wherein the intraocular implantfurther comprises at least one retention projection extending outwardlyfrom the tube for anchoring the intraocular implant in the eyeball. 12.A method of regulating an intraocular pressure according to claim 11wherein the tube passage is cylindrical, and wherein a diameter of thetube passage is substantially smaller than a length of the tube passage.13. A method of regulating an intraocular pressure according to claim 11wherein the diameter of the tube passage is about 300 micrometers orless.
 14. A method of regulating an intraocular pressure according toclaim 11 wherein the intraocular implant is made of a plastic material.15. A method of regulating an intraocular pressure according to claim 11wherein the intraocular implant is made of silicone.
 16. A method ofregulating an intraocular pressure according to claim 11 wherein theintraocular implant is made by a molding operation.
 17. A method ofregulating an intraocular pressure according to claim 11 wherein theintraocular implant is made of metal.
 18. A method of regulating anintraocular pressure according to claim 11 wherein the at least oneretention projection and the tube are made from separate pieces that arejoined together.
 19. A method of regulating an intraocular pressureaccording to claim 18 wherein the separate pieces forming the at leastone retention projection and the tube are joined together by welding.